Filtration question

This is a discussion on Filtration question within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
I'm currently using a DIY bucket filter for my pond, as shown in this picture. (clickable thumbnail)
Now my question is, should I keep ...

I'm currently using a DIY bucket filter for my pond, as shown in this picture. (clickable thumbnail)

Now my question is, should I keep the lid on the filter or should I remove it and expose it to air and sunlight? Which aids the growth of beneficial bacteria faster? I've been keeping the lid on and I only open it when I'm checking for any clogging. There's a faint smell when I open it, similar to rotting leaves. Is this a good sign? I'm thinking it's a sign of the bacteria doing their job, but I might be wrong.

Do you have a water test kit? If your ammonia and nitrites are staying at zero, I would say the filter is doing its job.
I would worry about unwanted algea building up inside the filter if you leave the lid off, but if you are willing to clean it out, no real harm in trying, I do not believe sunlight will help in nitrate bacteria growth though.

I'm still cycling so my readings aren't constant/established yet. It's a fish-in cycle, (I was planning to go fishless) since my brother bought some fish on an impulse. But the fish seem okay, though and I've read that the larger the tank, the easier it is on the fish. And this is a small outdoor pond around 200 gallons.

I would think that the bucket fillter with lid attached,would be much like a cannister filter which is sealed.I might place some lava rock the kind sold in bags at some lawn and garden stores, as opposed to larger pieces sometimes used for decorations, in the bottom of the bucket for bacteria to gather on. Could also drill some small holes in the lid to help keep debri out but allow oxygen in? Just some thoughts.Would not allow ammonia and or nitrites climb much higher than present readings indicate.

I'm not an expert but I'd leave the lid partially cracked to let air in. To me that would be like a bio-wheel. Bio-wheels are supposed to be good because the bacteria on the wheel use oxygen from the air instead of from the water. By letting air in I think you might accomplish the same affect.
I don't think I'd want the sun shining on this though. I wonder if the sun would kill the bacteria by getting the barrel too hot. (think of the interior of a car in the summer) Much like food in a kitchen must be kept above 140 to kill bacteria. I think the inside of this could get quite hot and kill the bacteria.

@1077
Yeah, any higher readings and I need to take some immediate action. I actually have some lava rock in it already, used in conjuction with filter mats. (They're called "japanese filter mats" here.)

@WisFish
I don't think it get's too hot, as even with the sun shining on it, the water inside when I dip my hand in is cool.

I guess oxygen from the air is beneficial to them, so I'll follow your advice. I'll be raising the cover a bit so air can come in.

Is it a trickle filter or is the lava rock and mats constantly submerged? If it's submerged then holes in the lid won't help oxygenate the filtration bacteria all that much. If water is trickling down through the mats and over the rocks with only a bit puddling on the bottom then some holes would be a huge help.

So I guess holes on the lid won't be helping much. Having the media submerged isn't that much of an issue, right? I think my water's oxygenated enough since I don't see my fish gulp at the surface of the water unless it's feeding time.

My ammonia and nitrite readings are somewhere below/around 0.25 but still not zero. I noticed a slight change it color from yesterday but it's not much. So it's still 0.25 for nitrite and ammonia. Fish are not showing ill effects and are eating well but I shouldn't be too complacent. This, hopefully, would drop to zero by next week. (4th week of cycling)

No, holes aren't going to do a whole lot for you. The surface area of the pond is so much greater than that in the bucket that it won't matter a whole lot whether or not the surface of the water in the bucket is well oxygenated. It's probably not a horrible idea to punch a hole or two in the lid just to keep the pressure inside and out equalized though.